A paper published in Nature Climate Change in April 2016 shows a widespread increase of growing-season leaf area over 25% to 50% of the global vegetated area, with the CO2 fertilization effect explaining 70% of the observed greening trend. Climate change explains 8% of the greening trend, predominantly in the high latitudes and the Tibetan Plateau. The study used three satellite leaf area index records to determine the greening and used ecosystem models to allocate the greening trends during 1982 - 2009 among four key drivers. Climatologist Nic Lewis comments says the increase in vegetation is considerably larger than suggested by previous studies.

Elevated levels of atmospheric CO2 have been conclusively shown to stimulate plant productivity and growth. The annual total monetary value of this benefit grew from $18.5 billion in 1961 to over $140 billion by 2011, amounting to a total sum of $3.2 trillion over the 50-year period 1961-2011. Projecting the monetary value of this positive externality forward in time reveals it will likely bestow an additional $9.8 trillion on crop production between now and 2050. (Values in constant 2005 $US. Current consumer prices are 1.2 X 2005 prices.)

A study of arid regions around the globe finds that a carbon dioxide "fertilization effect" has caused a gradual greening from 1982 to 2010. The satellite imagery data showed an 11 percent increase in foliage after adjusting the data for precipitation, air temperature, the amount of light, and land-use changes during the study period when CO2 concentrations increased by 14 percent.
"Satellites are very good at detecting changes in total leaf cover, and it is in warm, dry environments that the CO2 effect is expected to most influence leaf cover."

This study by Dr. Sherwood Idso shows that the world's forests increase their rates of carbon sequestering by 2.8 times in response to a 300 ppm increase in the CO2 content in the air. After two years of growth in a controlled experiment, trees in an ambient plus 300 ppm CO2 enriched environment were 2.8 times larger than the trees without CO2 enrichment.

This abstract shows that elevated levels of atmospheric CO2 causes a long-term biomass increase of 130% for conifer trees and 49% for deciduous trees in studies not involving stress components. However, stimulation of photosynthesis by elevated CO2 in long-term studies was similar for conifers (62 %) and deciduous trees (53 %).